Live Invertebrates

More than 95% of the Earth's animal species are invertebrates (animals without backbones). They can be found in most habitats. Many are found only in the sea and some groups living on the land are found world-wide. There are thought to be between 3 million and 15 million species in the world (47 000 species of vertebrates).

Invertebrates are important in the functions and processes of most ecosystems. They are spectacular, abundant and diverse. They include the Giant Squid at 18m long and gall mites, which are less than .25mm long.

Invertebrates have played an important role in discoveries about how the nervous system works. The squid, aplysia (sea hare), leech, horseshoe crab, lobster, and cockroach have all provided scientists with models by which to study the nervous system. The squid even helped win the Nobel Prize in Physiology or Medicine in 1963.

Invertebrates are useful animals to study because their nervous system functions in basically the same way as that of vertebrates. Neurons in all animals work using an electrochemical process. Because the nervous system of invertebrates is less complex than that of vertebrates, it is easier to isolate and study neural functions in these animals without backbones.

Annelids - The annelids, collectively called Annelida (from Latin annellus "little ring"), are a large phylum of animals, comprising the segmented worms, with about 15,000 modern species including the well-known earthworms and leeches.

Arthropods - Arthropods (phylum Arthropoda) (from Greek meaning foot) are the largest phylum of animals and include the insects, arachnids, crustaceans, and others.

Chordata - Chordates (phylum Chordata) are a group of animals that includes the vertebrates, together with several closely related invertebrates.

Echinoderms - Echinoderms (Phylum Echinodermata, from the Greek for spiny skin) are a phylum of marine animals found at all depths. This phylum appeared in the early Cambrian Period and contains about 7,000 living species and 13,000 extinct ones.

Molluscs - The mollusks or molluscs are the large and diverse phylum Mollusca, which includes a variety of familiar animals well-known for their decorative shells or as seafood.

Nematodes - The nematodes or roundworms (Phylum Nematoda from Gr. nema, nematos "thread" + ode "like") are one of the most common phyla of animals, with over 20,000 different described species (over 15,000 are parasitic).

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